Visual display devices are used in computers to provide information in visual form to the user. Commonly known visual display devices include monitors used in personal computers, LCD (liquid crystal display) screens used in portable computers, and flat panel touchscreen displays such as those used in point-of-purchase computers.
This invention is particularly directed to visual display devices used in portable computers, such as laptops, notebooks, and palmtops. These portable computers typically employ LCD screens. One important design consideration for portable computers is power consumption. It is desirable to design portable computers to consume very little power during operation, thereby extending the duration of computer usage between battery charges. Visual display devices represent a significant portion of the power consumption for the entire portable computer. There is a need to design visual display devices with low power consumption.
Conventional visual display devices convert a string of digital data into visual information that can be displayed on the screen. For efficient handling of the data, the data is first organized in a memory according to a preset format representative of the screen layout. The formatted data pattern is then efficiently transferred to the visual display device for immediate display. The data is sent to the screen many times per second to "refresh" the screen. If the visual information displayed on the screen is not changed, the same data is used over and over during screen refresh. This refreshing process consumes power.